1. Technical Field of the Invention
This invention relates to water soluble derivatives of polyethylene terephthalate. In another aspect, this invention relates to the conversion of solid, water insoluble polyethylene terephthalates to liquid polymeric water soluble derivatives useful as water thickening agents, etc.
2. Prior Art
When terephalic acid is reacted with a diamine, the representative reaction product is a water-insoluble liquid. When terephthalic acid (normally in the form of the dimethyl ester, dimethyl terephthalate, is reacted with a glycol such as ethylene glycol, water-insoluble polymers are formed, characterized by the formula: ##STR1## wherein n is a number having a value of about 50 to about 2,000.
It is known to react dibasic acids such as adipic acid, azealic acid, terephthalic acid, polymers of fatty acids, etc. with diamines of the formula: EQU H.sub.2 NCH.sub.2 CH.sub.2 --(HNCH.sub.2 CH.sub.2).sub.x NH.sub.2 (II)
where x is a number having a value of 0 to 4 to form reaction products useful in the preparation of coatings and adhesives as shown, for example, by U.S. Pat. No. 4,128,525 and U.S. Pat. No. 4,167,498.
An extensive body of technical knowledge has arisen relating to the preparation of solid polyethylene terephthalate from suitable monomers such as ethylene glycol and dimethylterephthalate.
Polyethylene terephalate is widely used in the manufacture of beverage bottles and the disposal of used bottles in an environmentally acceptable manner present a major problem. One proposed solution has been to convert the used polymer into an unsaturated polyester that can be used to make moldings such as boat hulls (Plastics Technology, September 1981). The used bottles are reported to have been used as raw materials in the manufacture of industrial strappings, fiber fill for pillows, sleeping bags and the like, synthetic lumber and corrugated rubber (C&E News, Jan. 5, 1981, p. 30).
Copending coassigned Sellstrom et al. U.S. patent application Ser. No. 510,696 filed July 5, 1983 and entitled "Novel Amine Curing Agents and Epoxy Resins Cured Therewith" (D#80,060) discloses oil soluble, essentially water insoluble compositions useful in the curing of epoxy resins prepared by dissolving polyethyleneterephthalate in an amine curing agent, such as an amine having formula (III), below: EQU NH.sub.2 --CH(CH.sub.3)--CH.sub.2 [O--CH.sub.2 CH(CH.sub.3)].sub.x NH.sub.2 (III)
wherein x has a value of 2 to 40.